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Thread: Star disappeared???

  1. #1

    Star disappeared???

    Hi all

    This has been bugging me now since Saturday. A couple of friends and I were stargazing over the weekend, saw a couple of shooting stars and satellites. Two of us saw, what I thought at the time, a 'nova' of some sorts. Over a period of around two seconds max, a star appeared to become brighter and then faded away completely.

    Right at that time, I exclaimed "wow that was a supernova!"

    Of course, it is more likely to be something else entirely as supernova's tend to last for quite a while, not a mere two seconds. The only explanation I have come up with is that this was a relatively low-orbit satellite that, for the briefest of moments, reflected some light (star- or earth bound) in my general direction. But, what I saw over the two second period was completely stationary, it did not appear to "move" across the sky as with most satellites, which often tend to move rather quickly.

    Details of my observation:

    Date: Saturday, 9th September
    Time ~22:30-23:00
    Latitude: 5241'30.93"N
    Longitude: 259'1.32"W
    Direction observed: South - South West

    Any ideas as to what it might have been?

  2. #2
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    I haven't had a chance to check just yet but it sounds very much like a flare from one of the Iridium satellites.
    The table below is for what you might see from Atlanta tomorrow night for flares.
    http://www.heavens-above.com/IridiumFlares.aspx

    Go the Heavens Above site and plug in your coordinates. Then select the item for Iridium Flares and look for the date of your sighting.

    Sent from my iPhone using Tapatalk Pro
    Last edited by schlaugh; 2017-Sep-15 at 02:17 PM. Reason: typo

  3. #3
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    Quote Originally Posted by stevenspray View Post
    Hi all

    This has been bugging me now since Saturday. A couple of friends and I were stargazing over the weekend, saw a couple of shooting stars and satellites. Two of us saw, what I thought at the time, a 'nova' of some sorts. Over a period of around two seconds max, a star appeared to become brighter and then faded away completely.

    Right at that time, I exclaimed "wow that was a supernova!"

    Of course, it is more likely to be something else entirely as supernova's tend to last for quite a while, not a mere two seconds. The only explanation I have come up with is that this was a relatively low-orbit satellite that, for the briefest of moments, reflected some light (star- or earth bound) in my general direction. But, what I saw over the two second period was completely stationary, it did not appear to "move" across the sky as with most satellites, which often tend to move rather quickly.

    Details of my observation:

    Date: Saturday, 9th September
    Time ~22:30-23:00
    Latitude: 5241'30.93"N
    Longitude: 259'1.32"W
    Direction observed: South - South West

    Any ideas as to what it might have been?
    That's a very helpful log of the observation. I of course immediately thought that you must've seen an Iridium flare, but a check of heavens-above.com doesn't show any flares at that time and place (unless I made an error).

    However, there are some impressive ones the next two mornings, and some following those, in the early evenings.

  4. #4
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    There was an Iridium flare at 21:28 BST in your area, but low in the north, moving from south to north.

    Also, there is a LOT of space junk orbiting the Earth and sometimes a satellite flares briefly. It could have been a spent rocket stage or a tumbling satellite. For example, a Japanese satellite called H-2A R/B went over your spot at 22:20 and was magnitude 1.8, which is fairly bright. Typically satellites appear as a moving "star" rather than a single flare, but they can also change brightness if tumbling. The Iridium satellites are an exception and often show as a moving object, then flare very brightly, then fade. The satellite's large, bright antenna panels cause the flares.

    Lots of good information on Iridium flares is in this Wikipedia link.

    ETA: You should have a very good view of the ISS over several days starting on September 28 through October 4. Check the Heavens Above site for the details (or any ISS tracking app or site).
    Last edited by schlaugh; 2017-Sep-15 at 02:51 PM.

  5. #5
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    I agree that it was mostly likely a satellite flare.

    It is possible it was a meteor. Especially if it was coming straight at you (or almost straight at you), it might just appear a dot that got brighter then faded, rather than as a streak across the sky.

    If it was a naked-eye bright supernova, it would not have faded that fast; and the astronomy media (including CQ) would still be buzzing about it. And there are so many professional and amateur observers looking for such things, it would have been spotted.
    Last edited by Swift; 2017-Sep-15 at 02:54 PM.
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  6. #6
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    You probably got it right with the reflecting satellite (or space junk). I would suggest you use the Heavens Above site others have already mentioned, and try to catch a predicted Iridium flare for your location (make sure you enter it as precisely as possible). Once you've seen (and no doubt enjoyed) it you can compare it to what you experienced earlier. And then use your newfound knowledge to amaze your friends.

    I believe the free Heavens Above app can give you an alarm when you have it on a smart phone and it detects an imminent flare for your current location... but I haven't tried that option.
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  7. #7
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    Unfortunately (for me anyway) Heavens Above only offers an Android app. But there are others.


    Sent from my iPhone using Tapatalk Pro

  8. #8
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    Anyone have data for where ENVISAT was at the time?

    That thing is a hoss'
    https://en.wikipedia.org/wiki/Envisa...Envisatmod.jpg

    --and it's loss grieved me even more than Cassini.

  9. #9
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    Iridium satellites are low enough that motion would likely be noticed.
    There are plenty of other satellites and boosters in all sorts of orbits
    that would appear to be motionless for a few seconds, or longer.

    I described here (more than once, I think) seeing a pair of relatively
    bright flashes several seconds apart in apparently the exact same
    location while casually looking for Perseid meteors just outside my
    back door, a decade or two ago. I'd have to find one of those posts
    for the details. It was surprising that there was no motion between
    the flashes. I think my best guess was a rotating object in geosynch,
    GTO, or Molniya orbit.

    -- Jeff, in Minneapolis
    http://www.FreeMars.org/jeff/

    "I find astronomy very interesting, but I wouldn't if I thought we
    were just going to sit here and look." -- "Van Rijn"

    "The other planets? Well, they just happen to be there, but the
    point of rockets is to explore them!" -- Kai Yeves

  10. #10
    Wow thank you for all the replies everyone (not sure why I wasn't notified of any) I think I can now sleep sound again tonight! Iridium flares is something I'm aware of but this never even crossed my mind. I always check where the ISS is when out stargazing but can now add heavensabove to my repertoire.

    Thanks again all.

  11. #11
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    Here's a geostationary satellite flare caught on a timelapse camera. Note that it stays still, even tough the stars are moving. This difference would not be easily apparent to the naked eye.
    https://www.youtube.com/watch?v=KFTFywzVI_E

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